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Find magnitude of acceleration on a Ca ion, given electric field.

  1. Feb 3, 2013 #1
    1. The problem statement, all variables and given/known data

    The electric field strength across a typical cell membrane is about 107 N/C. Given this information, find the magnitude of the acceleration of a single charged Ca+1 ion as it penetrated throught the cell wall. Ignore any resistive forces.
    One atomic mass unit is 1.66 x 10-27 kg.

    2. Relevant equations
    F = ma
    F=q0E

    3. The attempt at a solution

    I was thinking of multiplying the charge with how many protons a Ca ion has so:

    F=q0E
    = (20[itex]\bullet[/itex]1.6*10-19C)(107 N/C)
    = 3.2*10-11 N

    Then I manipulated for acceleration in F=ma and got 1.93*1016 m/s?

    Is this the correct method for finding the magnitude of acceleration?
     
  2. jcsd
  3. Feb 3, 2013 #2

    cepheid

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    Ca1+ means that the charge on the ion is only unbalanced by ONE proton charge. I.e. the atom has lost one electron, leaving it with a net positive charge due to ONE extra proton whose charge is unbalanced.
     
  4. Feb 3, 2013 #3
    So would it be correct if I just use q=+1.6*10-19 C in the formula to find force?
     
    Last edited: Feb 3, 2013
  5. Feb 3, 2013 #4

    cepheid

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    Yes.
     
  6. Feb 3, 2013 #5
    Okay so I used q=+1.6*10-19 C in the formula and got F = 1.6*10-12 N. To find the magnitude of acceleration, I manipulated for a in F = ma and got 9.64 * 1014 m/s as the answer but I inputted it in my online homework assignment and apparently it's wrong.

    Should I use a different formula to find acceleration?

    Edit: I used 1.66*10-27 kg as the mass.
     
  7. Feb 3, 2013 #6

    haruspex

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    That's one atomic mass unit. How many of those per calcium atom?
     
  8. Feb 3, 2013 #7
    To get atomic mass, do I need to add protons and neutrons in Calcium together? So 40?
     
  9. Feb 3, 2013 #8

    cepheid

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    Sounds about right to me.
     
  10. Feb 3, 2013 #9
    Sweet, I got the answer right! (2.41*1013 m/s) Thanks for all your help everyone! :D
     
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